CN104326637B - A kind of method for sludge treatment - Google Patents

Abstract

Embodiments provide a kind of method for sludge treatment, belong to field of sludge treatment, it is possible to process mixing sludge rationally and effectively, solve city environmental pollution problem.Described method for sludge treatment, including: municipal sludge and steel mill's mud are mixed, obtains mixing sludge；After described mixing sludge is ground, sieves, it is carried out heat exchange and sends in reactor；In described reactor, described mixing sludge in the supercritical state with oxidant generation oxidation reaction, reaction of formation product；Described reaction product carries out high-pressure gas-liquid separation after cooling, obtains power tail gas, CO₂Gas and the pulp water rich in metal-oxide.The present invention can be used in the Combined Treatment of municipal sludge and steel mill's mud.

Description

A kind of sludge treatment method

technical field

The invention relates to the field of sludge treatment, in particular to a sludge treatment method.

Background technique

In recent years, with the rapid development of the economy and the acceleration of the urbanization process, the amount of municipal sewage treatment has increased, resulting in an increase in the amount of sludge produced after flocculation and settlement in the process of sewage treatment. In addition, with the development of the steel industry, a large amount of sludge from steel mills is also produced. Municipal sludge and steel mill sludge constitute the main source of mixed sludge, among which steel mill sludge is rich in transition metal elements such as Fe, Mn, Ni, Cr, Mo, V, Ti, Zn, Cu , As, etc., are common components in steel mill sludge, and municipal sludge has a high calorific value. But both contain large amounts of water, making them difficult to recycle economically.

At present, most of the mixed sludge is treated by the traditional sludge incineration method, that is, after the sludge is collected, dehydrated and dried, a large amount of combustibles are added to ignite it, and then put into the incinerator for incineration. Due to the high moisture content of sludge, this incineration method will result in low furnace temperature, insufficient combustion, and less recoverable heat, so coal, petroleum coke and other fuels with higher calorific value are usually mixed into it. However, after combustion, there will be more solid residues of insufficient combustion, and the exhaust gas contains a large amount of toxic and harmful gases such as sulfur oxides, nitrogen oxides, and dioxins. In severe cases, steel mill sludge will also produce A large number of heavy metal oxides PM2.5, PM10 and other dust particles, the metal elements, especially heavy metal elements, such as Ni, Cr, Cu, Zn, As, etc. will form tiny particles of metal oxides during high-temperature incineration. The collection and trapping of particles is very difficult, and it is easy to enter the atmosphere with the exhaust gas, which will have adverse effects on the atmosphere, soil, groundwater and human health.

Since there is no better related process technology for the joint treatment of municipal sludge and steel mill sludge, how to treat mixed sludge reasonably and effectively can not only make full use of the catalytic activity of metal ions in sludge, but also solve the problem of urban pollution. Environmental pollution is an important issue faced by those skilled in the art.

Contents of the invention

The embodiment of the present invention provides a sludge treatment method, which can reasonably and effectively process mixed sludge and solve the problem of urban environmental pollution.

In order to achieve the above object, embodiments of the present invention adopt the following technical solutions:

A sludge treatment method, comprising:

Mix municipal sludge and steel mill sludge to obtain mixed sludge;

After the mixed sludge is ground and sieved, it is exchanged for heat and sent into the reactor;

In the reactor, the mixed sludge undergoes an oxidation reaction with an oxidant in a supercritical state to generate a reaction product;

The reaction product is subjected to high-pressure gas-liquid separation after cooling to obtain power tail gas, CO ₂ gas and slag water rich in metal oxides.

Optionally, the steel mill sludge accounts for 5-30% by mass of the mixed sludge.

Optionally, the steel mill sludge includes a transition metal selected from Fe, Mn, Ni, Cr, Mo, V, Ti, Zn, Cu, in terms of the mass percentage of the steel mill sludge, Fe is 5 ～50%, Mn 0.1～10%, Ni 0.1～20%, Cr 0.1～15%, Mo 0.05～5%, V 0.01～3%, Ti 0.01～2%, Zn 0.02～ 5%, Cu is 0.1-10%.

Optionally, the reaction product is subjected to high-pressure gas-liquid separation after cooling to obtain power tail gas, _CO gas and slag water rich in metal oxides, including:

performing a first-stage high-pressure gas-liquid separation on the reaction product in the first high-pressure gas-liquid separator to generate power tail gas and intermediate reaction products;

The intermediate reaction product is subjected to secondary high-pressure gas-liquid separation in the second high-pressure gas-liquid separator to generate _CO gas and slag water rich in metal oxides.

Optionally, the oxidizing agent is selected from any one of air, oxygen and hydrogen peroxide.

Optionally, the operating pressure of the oxidation reaction is 22-30 MPa, and the temperature is 380-900°C.

Further, the operating pressure of the oxidation reaction is 22-26 MPa, and the temperature is 420-650°C.

Optionally, the residence time of the reaction product in the first high-pressure gas-liquid separator is 5-60 minutes.

Further, the residence time of the reaction product in the first high-pressure gas-liquid separator is 15-40 minutes.

Optionally, the inlet temperature of the first high-pressure gas-liquid separator is below 31°C, and the outlet pressure is above 7.38MPa.

Optionally, before or after grinding and screening the mixed sludge, a compounding agent is added to the mixed sludge to increase the concentration of the mixed sludge.

The embodiment of the present invention provides a sludge treatment method. This method utilizes the special properties of water in the supercritical state to make the mixed sludge and oxidant react rapidly in supercritical water to completely decompose the mixed sludge to generate _CO2 gas and slag water rich in metal oxides. In this method, not only _CO2 can be utilized as a resource, but also N, S, and P elements in organic matter can be effectively transformed, and harmless treatment can be realized. At the same time, because steel mill sludge contains a large amount of transition metal elements, it plays a role in catalytic oxidation under supercritical water oxidation, and also realizes the enrichment of transition metal elements, which is especially beneficial to the sludge containing heavy metal elements. Harmless treatment in the later stage to reduce the negative impact on the environment.

Description of drawings

Fig. 1 is the flowchart of the sludge treatment method that the embodiment of the present invention provides;

Fig. 2 is the process flow chart of utilizing sludge treatment device to carry out sludge treatment provided by the embodiment of the present invention;

legend:

a1 is oxidant, a2 is raw water, a3 is compound sludge, b1 is tail gas 1, b2 is tail gas 2, b3 is slag water, b4 is sludge waste;

1 is the transmission system, 2 is the mixing tank, 3 is the pump 1, 4 is the grinder, 5 is the screening machine, 6 is the buffer tank, 7 is the pump 2, 8 is the raw material tank, 9 is the high pressure slurry pump, 10 is the heat exchange System, 11 is the reaction system, 12 is the high-pressure separation tank 1, 13 is the high-pressure separation tank 2, 14 is the pressure-reducing system, 15 is the expander, 16 is the pressure-reducing valve 1, 17 is the pressure-reducing valve 2, 18 is the booster pump Or compressor, 19 are coolers.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The sludge treatment method provided by the embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a flow chart of the sludge treatment method provided by the embodiment of the present invention. As shown in Figure 1, the embodiment of the present invention provides a kind of sludge treatment method, comprises:

S1: Mix municipal sludge and steel mill sludge to obtain mixed sludge;

In this step, municipal sludge and steel mill sludge are mixed to obtain mixed sludge, so as to realize coupled treatment of the mixed sludge. Among them, municipal sludge comes from urban sewage, and steel mill sludge can come from cold-rolled hot-rolled steel mills, blast furnaces, oxygen top-blown furnaces (top-blown furnaces, converters, bottom-blown furnaces), pickling and electroplating due to different processes and equipment. Operations, heat treatment plants, new open hearth furnaces, etc. Compared with municipal sludge, steel mill sludge is mainly composed of water and iron oxide particles washed from converter exhaust gas, and is rich in transition metal elements. It can be understood that the mixing of the steel plant sludge and municipal sludge usually needs to be uniformly mixed, and the mixing adjustment method can be obtained by a conventional method obtained by those skilled in the art, which is not specifically limited in the embodiment of the present invention.

S2: After the mixed sludge is ground and screened, it is exchanged for heat and sent into the reactor.

In this step, the mixed sludge needs to be ground and screened. This is because the sludge produced after sewage treatment often contains larger particles. If it is directly sent to the process device, it will easily cause pipeline blockage and affect the reaction. Therefore, pretreatment is required before being sent to the process unit. The sludge pretreatment includes sludge dilution, grinding, and filtration processes. The main treatment methods are grinding, sieving and filtering. For example, the speed of the grinder and the distance between the rotor and the stator of the grinder can be reasonably controlled to effectively grind the large particles in the mixed sludge, so as to ensure that the mixed sludge can proceed normally when it enters the next reaction. Before the large particles in the mixed sludge are effectively ground and sent to the reactor, they need to be heat exchanged, mainly because the supercritical oxidation reaction mainly occurs in the reactor, and the temperature is relatively high. For the occurrence of critical reaction, heat exchange can be performed on the mixed sludge after grinding and screening. It can be understood that the temperature reached after the heat exchange is about the temperature at which the supercritical reaction occurs.

S3: In the reactor, the mixed sludge undergoes an oxidation reaction with an oxidant in a supercritical state to generate a reaction product.

Supercritical water refers to water in a special state whose temperature and pressure are higher than its critical point (T=374.15°C, P=22.12MPa). Supercritical water has the properties of both liquid and gaseous water. In this state, only a small amount of hydrogen bonds exist. The dielectric constant is similar to that of organic solvents. It has a high diffusion coefficient and low viscosity. Under a sufficiently high pressure, not only can organic matter and oxygen in mixed sludge be miscible with supercritical water in any proportion, but also inorganic matter, especially salts, can be separated from supercritical water.

In this step, the special properties of water in the supercritical state are used to rapidly react the mixed sludge and the oxidant in the supercritical water to form reaction products, so as to completely decompose the mixed sludge. Among them, the main reactions are:

C+ _H2O →CO+ _H2

C+2H ₂ O→CO ₂ +2H ₂

CO+ _H2O → _CO2 + _H2

CO+3H ₂ →CH ₄ +H ₂ O

CO ₂ +4H ₂ →CH ₄ +2H ₂ O

C+O ₂ →CO ₂

2CO+O ₂ →2CO ₂

CH ₄ +2O ₂ →CO ₂ +2H ₂ O

2H ₂ +O ₂ →2H ₂ O

The reaction product after the reaction of the mixed sludge and the oxidant in the supercritical state mainly includes CO, N ₂ , O ₂ , CH ₄ and a small amount of CO ₂ gas, and the slag water of the mixed sludge after the reaction. Since CO, N ₂ , O ₂ , CH ₄ and a small amount of CO ₂ gas can drive the expansion agent to do work and generate electricity after separation, CO, N ₂ , O ₂ , CH ₄ and a small amount of CO ₂ are referred to as power exhaust.

S4: The reaction product is subjected to high-pressure gas-liquid separation after cooling to obtain power tail gas, CO ₂ gas and slag water rich in metal oxides.

In this step, the reaction product generated by the supercritical reaction needs to be cooled and then sent to the high-pressure gas-liquid separator for high-pressure gas-liquid separation. This is mainly because the supercritical reaction occurs in the reactor, and the reaction temperature is relatively high. , while the separation of CO ₂ gas and other power tail gas in the high-pressure gas-liquid separator needs to be operated according to the critical pressure and critical temperature of CO ₂ gas, so the reaction product needs to be cooled, and the cooling temperature is about to CO ₂ The critical temperature of the gas is below the critical temperature to ensure that the CO ₂ gas and the power tail gas are fully and effectively separated. It can be understood that the critical pressure can be determined according to the percentage of _{CO 2} in the gas component. pressure.

It should be noted that, in the embodiment of the present invention, the mixed sludge includes municipal sludge and steel mill sludge. It is understandable that there are many places where steel mill sludge is produced, such as cold-rolled hot-rolled steel mills, blast furnaces, oxygen top-blown furnaces (top-blown furnaces, converters, bottom-blown furnaces), pickling and electroplating operations, heat treatment plant, etc., so there is no specific limitation on the specific source of sludge, as long as it is sludge, whether it only treats municipal sludge or only steel mill sludge, or whether it is joint treatment of municipal sludge and steel mill sludge, All can be treated by using the sludge treatment method provided by the present invention.

The embodiment of the present invention provides a sludge treatment method. This method utilizes the special properties of water in the supercritical state to make the mixed sludge and oxidant react rapidly in supercritical water to completely decompose the mixed sludge to generate _CO2 and other gases and slag water rich in metal oxides. In this method, not only _CO2 can be utilized as a resource, but also N, S, and P elements in organic matter can be effectively transformed, and harmless treatment can be realized. At the same time, since steel mill sludge contains a large amount of transition metal elements, it plays a role in catalytic oxidation under the action of supercritical water oxidation, and also realizes the enrichment of transition metal elements, which is especially beneficial to the sludge containing heavy metal elements. Harmless treatment in the later stage to reduce the negative impact on the environment.

In one embodiment of the present invention, the steel plant sludge accounts for 5-30% by mass of the mixed sludge. In order to rationally utilize and treat steel mill sludge and municipal sludge, in this embodiment, the addition ratio of steel mill sludge and municipal sludge is scientifically controlled. This is mainly because, if the ratio is too low, the content of metal elements that play a catalytic role in the steel mill sludge is insufficient, it is difficult to play a catalytic role, or the ideal catalytic conditions cannot be reached; if the ratio is too high, it will affect The calorific value of the mixed sludge, of course, although the calorific value of the mixed sludge can be adjusted by adding other auxiliary fuels such as methanol, ethanol, waste engine oil, etc. to ensure the normal self-heating chemical reaction process, but if it can be more In order to control the ratio of steel mill sludge to municipal sludge in a reasonable way, it is not necessary to add other fuels to it, thereby controlling operating costs. It can be understood that the steel mill sludge accounts for 10%, 15%, 20%, 25% and so on of the mass percentage of the mixed sludge.

In one embodiment of the present invention, the steel mill sludge includes a transition metal selected from Fe, Mn, Ni, Cr, Mo, V, Ti, Zn, Cu, in order to account for the mass percentage of the steel mill sludge Calculated, Fe is 5-50%, Mn is 0.1-10%, Ni is 0.1-20%, Cr is 0.1-15%, Mo is 0.05-5%, V is 0.01-3%, and Ti is 0.01-2%. , Zn is 0.02 to 5%, and Cu is 0.1 to 10%. The steel plant sludge is rich in a large amount of transition metals, and these transition metals can play a role in catalytic oxidation under supercritical water oxidation, thereby speeding up the reaction time of the overall reaction, reducing the activation energy of the reaction, and optimizing the process operating conditions . Regulating the ratio of the transition metals in the steel mill sludge to the above ratio range can make the transition metals in the steel mill sludge reach ideal catalytic conditions without affecting the calorific value of the mixed sludge. In this way, normal self-heating chemical reactions can be guaranteed during the coupled treatment of steel mill sludge and municipal sludge.

In an embodiment of the present invention, the reaction product is subjected to high-pressure gas-liquid separation after cooling, and obtaining power tail gas, _CO gas and slag water rich in metal oxides includes: in the first high-pressure gas-liquid separator The reaction product is subjected to primary high-pressure gas-liquid separation to generate power tail gas and intermediate reaction product; the intermediate reaction product is subjected to secondary high-pressure gas-liquid separation in the second high-pressure gas-liquid separator to generate _CO2 gas and slag water rich in metal oxides.

In this embodiment, the reaction product needs to be cooled first, and then sent to the first high-pressure gas-liquid separator for separation. In a preferred embodiment of the present invention, the inlet temperature of the first high-pressure gas-liquid separator is controlled below 31° C., and the outlet pressure is controlled above 7.38 MPa. This can ensure that the CO ₂ gas and the remaining slag water after the reaction still exist in a liquid state, thereby realizing separation from the power tail gas.

In this embodiment, the separated CO ₂ gas and the remaining slag water after the reaction are sent to the second high-pressure gas-liquid separator for separation. It should be noted that the inlet pressure of the second high-pressure gas-liquid separator still needs to be kept above 7.38MPa at this time, so that _CO gas and the remaining slag water after the reaction can enter the second high-pressure gas-liquid separator together to obtain separate. In the second high-pressure gas-liquid separator, _CO2 gas is decompressed and separated through the decompression system. Since only _CO2 gas remains in the gas at this time, high-purity _CO2 gas can be obtained after separation. It can be understood that the decompression system can use a decompression valve to control the pressure, and can also use a capillary decompression device to reduce the pressure to normal pressure. After the _CO2 gas is separated, the slag water in the second high-pressure gas-liquid separator is also separated by decompression. It should be noted that the slag water at this time can be further separated into solid slag and slag water, wherein the solid slag can be used to recover flocculants and metal oxides, and the slag water can be recycled as raw water for reuse in the mixing mud In preparation. It can be understood that, regarding the subsequent treatment of slag water, those skilled in the art can perform treatment according to actual needs.

In an embodiment of the present invention, the oxidizing agent is selected from any one of air, oxygen and hydrogen peroxide. Selecting the above-mentioned gases as the oxidizing agent can satisfy the occurrence of the oxidation reaction under supercritical conditions, and can also avoid introducing other impurities into the reaction.

In an embodiment of the present invention, the operating pressure of the oxidation reaction is 22-30 MPa, and the temperature is 380-900°C. The operating pressure may be 24, 26, 28 MPa, and the temperature may be 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C. Selecting the operating pressure and temperature of the oxidation reaction within the above range can better ensure the occurrence of the oxidation reaction. In a preferred embodiment of the present invention, the operating pressure of the oxidation reaction is 22-26 MPa, and the temperature is 420-650°C.

In an embodiment of the present invention, the residence time of the reaction product in the first high-pressure gas-liquid separator is 5-60 minutes. The residence time may be 10, 20, 30, 40, 50 min. Reacting the mixed sludge and the oxidizing agent in the reactor for a period of time can ensure the full reaction of the mixed sludge and the oxidizing agent. In a preferred embodiment of the present invention, the residence time of the reaction product in the first high-pressure gas-liquid separator is 15-40 minutes.

In one embodiment of the present invention, before or after grinding and screening the mixed sludge, a compounding agent is added to the mixed sludge to increase the concentration of the mixed sludge. The compounding agent can be added to the mixed sludge before grinding and sieving, or after grinding and sieving, the purpose is to increase the concentration of the mixed sludge, and the compounding agent can use lignosulfonate, for example and humate mixture. It can be understood that this embodiment does not limit the selection of the compounding agent, as long as the concentration of the mixed sludge can be reasonably increased, those skilled in the art can use it.

The process flow of the sludge treatment provided by the present application using a sludge treatment device will be described in detail below with reference to FIG. 2 .

As shown in Figure 2, the raw materials a2 and a3 are transported to the mixing tank (2) according to a certain ratio, and after being stirred evenly, they are transported to the grinder (4) by the pump 1 (3), and the sludge slurry after grinding is passed through the screening machine (5) After filtering, the upper layer of the filter is waste material (b4), and the sludge in the lower layer enters the buffer tank (6), and is transported to the raw material tank (8) by the pump 2 (7). The raw sludge is transported to the heat exchange system (10) by the high-pressure slurry pump (9), enters the reaction system (11) after heat exchange, and reacts with the oxidant (a1) from the booster pump (18), and the reaction product is exchanged Enter cooler (19) after thermal system (10), enter first high-pressure gas-liquid separator (12) then, keep certain residence time, first high-pressure gas-liquid separator (12) upper end outlet product can promote expander ( 15) Generating power by generating power, and obtaining tail gas b1 (CO, N ₂ , O ₂ , CH ₄ and a small amount of CO ₂ ) after passing through the pressure reducing valve 1 (16). The product at the lower end of the first high-pressure gas-liquid separator (12) enters the second high-pressure gas-liquid separator (13), and the product at the upper end passes through the pressure reducing valve 2 (17) to obtain tail gas b2 ( _CO2 gas), and the product at the lower end enters the decompression System (14), the product after decompression is b3 (slag water rich in metal oxides), the water separated by b3 can be reused as raw material water (a2), and the solid slag separated by b3 is used to recover flocculant and metal oxide.

In order to better illustrate a sludge treatment method provided by the present invention, specific examples will be described in detail below. Among them, Table 1 lists the basic properties of municipal sludge, Table 2 lists the basic properties of steel mill sludge, and Table 3 lists the percentage content of metal elements in steel mill sludge.

Table 1 Basic properties of municipal sludge

Table 2 Basic properties of steel mill sludge

Remarks: ar is the result on received basis, d is the result on dry basis.

Table 3 Percentage of metal elements

Example 1

Use 95% of the 1# municipal sludge raw material, 5% of the 3# steel mill sludge raw material, the oxidizing agent is O ₂ , add a compound agent (a mixture of lignosulfonate and humic acid salt, the addition ratio is 1:0.5, the addition amount is 0.5wt‰), so that its concentration reaches 7%, the temperature of the control reaction system is 580°C, and the reaction pressure is 22MPa. The mixed sludge of municipal sludge and steel mill sludge is in the first high pressure gas The residence time in the liquid separator is 15 minutes. The outlet product at the upper end of the first high-pressure gas-liquid separator is depressurized by a pressure reducing valve to obtain a mixed gas such as CO, N ₂ , CH ₄ , which contains a small amount of CO ₂ gas. The first high-pressure The product at the outlet of the lower end of the gas-liquid separator enters the second high-pressure gas-liquid separator, and the product at the upper end is decompressed by a pressure reducing valve to obtain high-purity _CO2 gas, and the product at the lower end enters the decompression system, and the product after decompression is rich in metal oxide The chemical oxygen demand (COD) of the liquid in the slag water is 20mg/L, which meets the national first-level discharge standard, and can be reused as raw material water. The separated solid slag is used to recover flocculants and metal oxides.

Example 2-8

For the specific process of Examples 2-8, see Example 1, and for the relevant parameters in each example, see Tables 4-5.

Table 4 Examples 1-4

Example 1 Example 2 Example 3 Example 4 Municipal sludge raw material 1# sludge 95% 1# sludge 85% 2# sludge 90% 2# sludge 70% Steel mill sludge raw material 3# sludge 5% 4# sludge 15% 4# sludge 10% 5# sludge 30% oxidizing agent O ₂ Air O ₂ Air Concentration wt% 7 10 15 20 Reaction temperature °C 580 420 450 450 Reaction pressure MPa twenty two twenty three 25 twenty four residence time min 15 20 30 50 b3COD*mg/L 20 16 5 5

Note: COD* is chemical oxygen demand; municipal sludge and steel mill sludge are allocated according to percentage, totaling 100%.

Table 5 Example 5-8

Example 5 Example 6 Example 7 Example 8 Municipal sludge raw material 1# sludge 90% 1# sludge 85% 2# sludge 80% 2# sludge 75% Steel mill sludge raw material 3# sludge 10% 4# sludge 15% 4# sludge 20% 6# sludge 25% oxidizing agent O _{2 H2O2 _} Air O ₂ Concentration wt% 8 10 15 20 Reaction temperature °C 390 420 480 900 Reaction pressure MPa twenty three twenty three 26 26 residence time min 20 20 30 50 b3COD*mg/L 15 20 5 10

Note: COD* is chemical oxygen demand; municipal sludge and steel mill sludge are allocated according to percentage, totaling 100%.

It can be seen from the above that the sludge treatment method provided by the embodiment of the present invention can make the mixed sludge rapidly react with the oxidant in supercritical water to be completely decomposed, and generate _CO2 gas and slag water rich in metal oxides. This method can not only realize the resource utilization of _CO2 , but also effectively transform the N, S, and P elements in the organic matter, and realize the harmless treatment. At the same time, since steel mill sludge contains a large amount of transition metal elements, it plays a role in catalytic oxidation under the action of supercritical water oxidation, and also realizes the enrichment of transition metal elements, which is especially beneficial to the sludge containing heavy metal elements. Harmless treatment in the later stage to reduce the negative impact on the environment.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. However, the obvious changes or changes derived therefrom still fall within the scope of protection of the present invention.

Claims (11)

1. a method for sludge treatment, it is characterised in that including:

Municipal sludge and steel mill's mud are mixed, obtains mixing sludge；

After described mixing sludge is ground, sieves, it is carried out heat exchange and sends into reactor In；

In described reactor, described mixing sludge in the supercritical state with oxidant generation oxygen Change reaction, reaction of formation product；

Described reaction product carries out high-pressure gas-liquid separation after cooling, obtains power tail gas, CO₂ Gas and the pulp water rich in metal-oxide.

Method for sludge treatment the most according to claim 1, it is characterised in that described steel mill Mud accounts for the 5～30% of the mass percent of described mixing sludge.

Method for sludge treatment the most according to claim 1 and 2, it is characterised in that described Steel mill's mud includes the transition gold selected from Fe, Mn, Ni, Cr, Mo, V, Ti, Zn, Cu Belonging to, to account for the mass percentage of described steel mill mud, Fe is 5～50%, and Mn is 0.1～10%, Ni is 0.1～20%, and Cr is 0.1～15%, and Mo is 0.05～5%, and V is 0.01～3%, and Ti is 0.01～2%, Zn are 0.02～5%, and Cu is 0.1～10%.

Method for sludge treatment the most according to claim 1, it is characterised in that described reaction Product carries out high-pressure gas-liquid separation after cooling, obtains power tail gas, CO₂Gas and rich in gold The pulp water belonging to oxide includes:

In the first high-pressure gas-liquid separator, described reaction product is carried out one-level high-pressure gas-liquid to divide From, to generate power tail gas and intermediate reaction product；

In the second high-pressure gas-liquid separator, described intermediate reaction product is carried out two grades of high pressure gas Liquid separates, to generate CO₂Gas and the pulp water rich in metal-oxide.

Method for sludge treatment the most according to claim 1, it is characterised in that described oxidation Agent is selected from any one in air, oxygen and hydrogen peroxide.

Method for sludge treatment the most according to claim 1, it is characterised in that described oxidation The operation pressure of reaction is 22～30MPa, and temperature is 380～900 DEG C.

Method for sludge treatment the most according to claim 6, it is characterised in that described oxidation The operation pressure of reaction is 22～26MPa, and temperature is 420～650 DEG C.

Method for sludge treatment the most according to claim 4, it is characterised in that described reaction The product time of staying in described first high-pressure gas-liquid separator is 5～60min.

Method for sludge treatment the most according to claim 8, it is characterised in that described reaction The product time of staying in described first high-pressure gas-liquid separator is 15～40min.

Method for sludge treatment the most according to claim 4, it is characterised in that described The inlet temperature of one high-pressure gas-liquid separator is below 31 DEG C, and outlet pressure is at more than 7.38MPa.

11. method for sludge treatment according to claim 1, it is characterised in that to institute State mixing sludge be ground and sieve front or rear, in described mixing sludge, add complexing agent, To improve the concentration of described mixing sludge.